William h



(NoModel.)

W'. E. BROCK.

Grin'dstone.

No. 242,873.V Patented June 14,1881..A

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mmm me UNITED STATES PATENT OFFICE.

VILLIAM H. BROCK, OF CORONA, ASSIGNOR OF ONE-HALF TO JOIIN W.

ALEXANDER, OF NEW YORK, N. Y.

GRINDSTONE.

SPECIFICATION forming part of Letters Patent No. 242,873, dated June 14, 1881.

Application filed March 7, 1881. (No model.)

To all 'whom it may concern:

Be it known that I, WILLIAM H. BROCK, residing at Corona, county of Queens, and State of New York,haveinvented certain new and useful Improvements in Grindstones; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon, making a part of this specication.

This invention relates to stones or4 wheels employed for grinding, polishing, 86o., and whose surface abrades and wears away in use.

It has for its object the maintenance of a uniform rate of speed in the movement of the surface of the rotating stone, notwithstanding the reduction of its diameter by use, so that the face of the stone or wheel shall, with a constant motor, move at one and the same constant rate of speedindependentl y ofthe change in the circumference of the wheel resulting from its wear.

It consists in a combination, with the friction-wheel engaging the face of the grindstone to drive it, of suitable mechanism for throwing 'the friction wheel or pulley in and out of contact with the grindstone, and for securing contact, as required, until the stone is wholly worn away.

In the accompanying drawings, Figure l is a perspective view of my improved constantmotion grindstone and driving-pulley, and

Fig. 2 a top or plan view thereof.

A is a grindstone, of any quality or description adapted for grinding or polishing and which is liable to wear away in use. This stone is mounted in suitable bearings upon a frame or casing, B, in the customary manner, so as to revolve freely and truly upon its axis.

G is a smaller wheel or friction pulley, mounted in suitable bearings upon a sliding plate, D, which rest-s upon a second plate, E, adapted to tit upon the casingBin front of the stone. This second plate, E, is formed with lateral flanges e c, Fig. l, made to overlap and embrace the edges of the ange of the casing, and is secured to the casing by means of setscrews ff, working through the overlapping ilanges e e of the plate E against the inclosed flange of the casing.

When` the set-screws ff are loosened the plate E may be moved, to or from the grindstone; butit remains immovable when the setscrews are tightened up. The movement of the plate E permits of its adjustment in proper proximity to the face of the stone, as required, for the purpose of bringing the friction-wheel C into contact therewith.

The bearing-plate D, which rests and slides upon the adjustable casing-plate E, is guided and limited in its movement longitudinally to and fromthe stone by means of pins h h, which project upward from the casin g-plate E through longitudinal slots in the bearing-plate D. (See Fig. 2.)

The' friction-pulley C is mounted upon an axle or arbor, which, supportedin suitable journal-boxes upon the sliding bearing-plate D, extends out far enough on one side to receive a driving-pulley, G, Fig. 2, geared by a band, R, Fig. 1, to a suitable prime motor.

K K are crank-levers pivoted each to an ear or offset upon the sides ot the adjustable casing-plate E. The shorter arm of each lefVV ver passes up between pins S S, projecting from the sliding plate D, and its longer arm extends downward at an inclination forward to within ready reach ofthe operators foot at the other end of the stone, the long arms ot' the levers being united at their outer ends by a transverse connecting foot-bar, L, Fig. 1. By depressing the long arm of the levers their shorter arms are thrown in toward the `grindstone and operated to force the sliding ure, either by keeping his foot on thefoot-bar' L or by fastening down said bar by means of a latch, M, secured to the Casin g, and arranged to engage the lever K, (see Fig. 1,) or by other simple form of locking device.

The sliding plate D may be automatically withdrawn from contactwith the grindstone by means of a spring arranged to retract it, or by causing the shorter arm of one or both levers K to embrace a pin on the sliding plate D, so that when the long arm of the lever is lifted it shall in itself operate to carry back the plate and friction-pulley. In this case a spring` may be applied to operate upon the lever to effect the withdrawal of the pulley.

The'surface of the friction-pulley C is preferably made very hard and scored with diagonal grooves running from side toside, one set ot grooves being made to cross the other, as shown in the drawings, Fig. 2.

The grooves,wh`en properly out and sharpened, will serve to keep the face of the grindstone true and clean and in the best condition for effective work.

In the use ot my device the friction-wheel', driven with a constant uniform speed by the belt R, is brought into contact with the face oi' the grindstoue by a simple pressure of the foot upon the lever-bar L, and by contact with the stone produces its rotation, the rotation being maintained by keeping the foot upon the leverbar L, or by locking the lever in its operative position by means of the lat-ch Mor oth er equivalent device.

So fast as the grindstone wears awayin use the adjustable clamp-plate E is moved to ward it, so that the friction-pulley may always be readily brought into effective contact with its face by a movement ot' the levers K. As the rate of rotation of the friction-pulley is constant and uniform, so it will always produce a corresponding rate of speed in the face of the grindstone, and this rate will remain the same when the stone is reduced to the smallest possible diameter as when it was of largest size.

It is evident that, instead of moving the friction-pulley toward the face of the grindstone in order to produce an operative Contact of the and with devices for producing a movement ofthe plate D and pulley G to and' from the i'aoe of the grindstone, substantially as and for the purpose herein set forth.

In testimony whcreofI have signed my name to this specification in the presence of two subscribing` witnesses.

WILLIAM H. BROOK.

Witnesses:

DAVID A. BURR, IRvING DrcKrNsoN. 

